In the prior hand tools, such as spanners, the tool generally has driving portion and a handle. The driving portion is engaged to a screw means for driving the screw means to rotate repeatedly. However the driving portion is retained to the handle, that is, the driving portion cannot rotate with respect to the handle so that if the work environment is not suitable for locating the spanner. The operator will feel uneasy in operation and the operation is inefficiency.
There are some portions which aim at to an adjustable spanner for improving above mentioned defects, such as U.S. Pat. Nos. 5,419,221, 6,928,904 and Taiwan Patent No. 542053. In these prior arts, a pivotal portion is installed between a driving portion and a handle so that the driving portion is rotatable with respect to the handle. However the pivotal portion has a complicated structure and it is difficult to position the pivotal portion. In operation, the pivotal portion easily slides away when a screwing means is rotated. Moreover when the driving portion is engaged to the handle, for installing a buckling portion, the thickness of the driving portion and the handle are twice of a general spanner. Thereby the spanner cannot be inserted into a narrow space. Moreover a larger space is necessary for storing the spanner. Thereby it is impractical.
However the prior art has the following disadvantages. Firstly, the pivotal portion between the driving portion and the handle is too large to be stored. Thereby the structure of the pivotal portion is complicated so that the cost is high and the manufacturing efficiency is low. Furthermore, the operations for buckling and rotating the pivotal portion are inconvenient. The pivotal portion easily slides away in driving a screw means.